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Estimated Mass Removal by SVE <br /> Based on the assumption that gasoline has an average molecular weight of 120 grams/mole, <br /> the AS/SVE system has removed almost 5,000 pounds of gasoline, or approximately <br /> 600 gallons. Table 2-1 presents measured data considered in the estimate of cumulative <br /> gasoline removal. Cumulative gasoline removal is expected to taper off logarithmically over <br /> a several month period, as shown in Figure 2-2. <br /> I <br /> Table 2-1 <br /> Del Monte Disco Site <br /> i <br /> Soil Vapor Extraction <br /> Gauge Cumulative <br /> Engine Intake Extraction Operating Pressure Temperature TPH(g) <br /> ` Date PID( mv) (scfm) Time(hrs) (in H2O) (degrees F) Removed(lbs) <br /> r 2/16/95 6,000 86 309 -14 .86 2819 <br /> 3/1/95 3,200 75 110 -95 94 3184 <br /> 3/3/95 2,800 78 71 -75 82 3417 <br /> 317195 5,400 80 45 -45 84 3734 <br /> 3/12195 2,340 79 93 -39- 83 4021 . <br /> f <br /> 3/15/951 3,240 74 48 -30 84 4216 <br /> 4/4/951 1,373 58 1 1,130 -12 110 4847 <br /> 4/5/95 4,810 62 1 1,157 -38 104 4977 <br /> 1 <br /> Radius of SVE-Influence <br /> With an applied vacuum averaged between the two SVE wells of -28 inches of water, the <br /> differential vacuums measured in NP-2-45' and NP-2-65' were 0.31 and 1.2 inches of water, <br /> respectively. The NP-2 cluster is located a minimum distance of 23.8 feet from AS/SVE-1 <br /> and an average distance from both the AS/SVE wells of 25.4 feet. The radius of influence for <br /> the SVE wells is roughly 20 to 25 feet, with an applied vacuum of-28 inches of water. <br /> The SVE wells have been operated at vacuum pressures as high as -95 inches of water. At a <br /> higher operating pressure, the radius of influence could be much greater. Treatment of soil <br /> vapor by engine combustion currently requires dilution air to supply oxygen not present in <br /> adequate concentration in pure soil vapor. As soil vapor oxygen concentration increases with <br /> subsequent pore volume exchanges and declining biological respiration, the operating <br /> pressure of the vapor extraction system will increase with a decrease in dilution air. This will <br /> result in a greater radius of influence for the SVE wells. <br /> Oxygen Up-Take/Respiration Rate <br /> An oxygen up-take/respiration,rate test was conducted on March 12, 1995, to assess the <br /> r decline in dissolved oxygen concentration within -the treatment zone of the AS/SVE system <br /> after blowers were shut down. The test consisted of taking a time series of in situ dissolved <br /> r oxygen measurements in the two deepest NP-1 piezometers: NP-1-80' and NP-1-90.' <br /> Results of the test are presented in Table 2-2 and plotted in Figure 2-3. <br /> 5F010030981.doc 2-4 <br />